Insertion of the LINE-1 element in the C-MYC gene and immunoreactivity of C-MYC, p53, p21 and p27 proteins in different morphological patterns of the canine TVT

Abstract

The canine transmissible venereal tumor (TVT) affects the external genitalia of dogs by the natural transplant of viable tumor cells. Thus, this research aimed to diagnose and characterize TVT morphological patterns, identify the insertion of the LINE-1 element in C-MYC gene, by means of the polymerase chain reaction (PCR), and evaluate the immunohistochemical expression of C-MYC, p53, p21 and p27 proteins. The relationship between C-MYC and p53 proteins and their interference on the expression of p21 and p27 were also studied. For that, 20 samples of naturally occurring TVT were used, subjected to cytopathological, histopathological and immunohistochemical analysis, and to molecular diagnosis of neoplasia. The increased tissue expression and the correlation among C-MYC, p53, p21 and p27 proteins indicate reduction and/or loss of their functionality in the TVT microenvironment, with consequent apoptotic suppression, maintenance of cell growth and progression of neoplasia.Keywords: dog, cell , cytology, immunohistochemistry RESUMO O tumor venéreo transmissível canino (TVT) afeta a genitália externa de cães pelo transplante natural de células tumorais viáveis. Assim, esta pesquisa teve como objetivo diagnosticar e caracterizar TVT em padrões morfológicos, identificar a inserção do elemento LINE-1 em gene C-MYC, por meio da reação em cadeia da polimerase (PCR), e avaliar a expressão imuno-histoquímica do C-MYC

Cytomorphological, Molecular Diagnosis and Evaluation of Insertion of the LINE-1 Element in the C-MYC Gene in Canine Transmissible Venereal Tumor: Applicability in Veterinary Clinical Routine

“…Precisely because there are different cell lines with different biological behaviors, cytomorphological diagnosis in cases of CTVT has gained in importance in veterinary oncology in terms of therapeutics and prognosis [15]. The percentage of cytomorphological types found in our study was different from those mentioned in the literature, as reported in Amaral et al (2007) [10], in which the most frequent type was the plasmacytic type (52.53%), followed by the mixed type (29.11%) and finally, the lymphocytic type (18.36%) as well as in Gaspar's et al (2010) [16], in which the frequency of the plasmacytic type was 50%, lymphocytic 19% and mixed 31% and in the research by Lima et al (2016) the plasmacytic type represented 45% of the cases, followed by the lymphocytic type (30%) and lastly the mixed type (25%) [12]. Some researchers have already reported different subtypes according to the Brazilian regions in which the plasmacytic type was more frequent in the southeast compared to the south [10].…”

“…Morphologically, CTVT is classified in three cytomorphological types: (1) lymphocytic, characterized by more than 60% of round cells, with finely granular cytoplasm, central nucleus and a few intracytoplasmic vacuoles; (2) plasmacytic, characterized by containing more than 60% of cells with a broad cytoplasm, eccentric nuclei and a large amount of vacuoles; and (3) mixed, presenting both lymphocytoid and plasmacytoid cells, neither of which exceed 59% [10,11]. Of them, the plasmacytic type is the most common cytomorphological type, and is related to chemoresistance [10,12,13]. Hence, due to its prognostic and predictive value, the determination of the cytomorphological classification has gained importance in veterinary clinical practice.…”

Nasal transmissible venereal tumours in 12 dogs – a retrospective study

“…In difficult cases additional analyses such as immunohistochemistry or detection of rearrangement LINE-1-c-myc by polymerase chain reaction may be needed. The insertion of a transposable genetic element sequence (known as LINE, long interspersed element) to the first exon of the C-MYC gene is a specific molecular rearrangement of TVT [3] [20].…”

Expression of PCNA, MMP-9, p53, Bax and Bcl-2 in canine transmissible venereal tumors

“…The origin of TVT is not shaped by the neoplastic transformation of normal cells. On the contrary, the development and evolutionary process of cells occur as a result of the transmission of clonal cells that pass from infected dogs to healthy dogs (Lima et. al., 2016).…”